Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich.
mehr Informationen...
One of the major challenges facing the application of layered LiNiO2 (LNO) cathode materials is the oxygen release upon electrochemical cycling. Here it is shown that tailoring the provided lithium content during synthesis process can create a disordered layered Li1‐xNi1+xO2 phase at the primary particle surface. The disordered surface, which serves as a self‐protective layer to alleviate the oxygen loss, possesses the same layered rhombohedral structure (R3¯$\bar{3}$m) as the inner core of primary particles of the Li1‐xNi1+xO2 (x ≈ 0). With advanced synchrotron‐based x‐ray 3D imaging and spectroscopic techniques, a macroporous architecture within the agglomerates of LNO with ordered surface (LNO‐OS) is revealed after only 40 cycles, concomitant with the reduction of nickel on the primary particle surface throughout the whole secondary particles. Such chemomechanical degradation accelerates the deterioration of LNO‐OS cathodes. Comparably, there are only slight changes in the nickel valence state and interior architecture of LNO with a thin disordered surface layer (LNO‐DS) after cycling, mainly arising from an improved robustness of the oxygen framework on the surface. More importantly, the disordered surface can suppress the detrimental H2 ⇋ H3 phase transition upon cycling compared to the ordered one.
Advanced synchrotron‐based nano‐resolution spectro‐tomography techniques are utilized to investigate the mesoscale chemomechanical degradation mechanism of LiNiO2 cathode materials. A 3D macroporous architecture coupled with a reduction of Ni on the primary particle surface is observed in the LNO‐OS electrode after 40 cycles. Regulation of surface antisite defects in the surface region of LiNiO2 can effectively mitigate the mechanical and structural degradation.